Amphibious pump

ABSTRACT

An amphibious pump is provided including a wet type motor with coolant and an absorbing mechanism of the expansion of the coolant inside the motor chamber, dividing it into two chambers, at least one expansion joint between an internal chamber of the motor, hermetically closed, and an equalization inner chambers and a means to equalize the internal pressure for the pumped fluid. The electric motor is immersed m a cooling liquid, usually oil, in a chamber, and, the other camera is filled with the aqueous solution, which communicates with the outside through the equalizer assembly, which can, for example, comprise a rubber mask with micro holes, which allows the exchange of water between the outer chamber and the chamber of the motor.

TECHNICAL FIELD

The present disclosure refers to a fluids pump which can work submerged or not, being generally known in the state of art as amphibious, equipped with art wet type electric motor filled with coolant typically an oil, which allows pumping fluids of high and low temperature and which operates at high pumping pressures. It has the application equipment in various areas, such as sanitation, mining, steelmaking, ethanol plants, industrial processes and others.

BACKGROUND OF RELATED ART

The state of art particularly refers to the submerged pumps with dry-type electric motors. In this type of pump the motor is protected by a mechanical seal system, which turns out to be a limiting factor in the pressure level that the pump can operate, as in the case of high pressures external to the motor housing runs the risk of breaking this mechanical seal, causing damage to the windings and motor bearings.

In relation to the dry type pumps belonging to the state of technology, one can highlight, for example, the submersible totally dry motor pump described in PI8900494-9. This pump is provided with fully dry electric, motor located within a motor housing.

Externally to the motor housing there is an outer wrapping, and an annular passage formed therebetween. In operation, water pumped by the impeller is directed to the annular passage and discharged through the pump outlet.

Among the objectives of the invention described in PI8900494-9 was the one to provide a fully dry submersible motor pump, able to work under conditions of higher pressures than their predecessors pumps, without its sealing system collapsing, preserving the completely dry condition needed to the run of the electric motor. To decrease solicitation on the sealing system and increase the value of maximum working pressure of the pump, the invention described in PI8900494-9 proposes an air camera disposed below the motor housing, separating one from another through a hermetic disc. Below the hermetic disk, a consistent sealing system is proposed, responsible for establishing a hermetic seal between the motor housing and the air camera.

The concordant seal system proposed in PI8900494-9 is comprised of a sealing means and a pressure compensator. The sealing medium is responsible for sealing between the pump shaft and the hermetic disc And the pressure compensator is mounted on the air camera and employs a foldable bellows-shaped wrap. Internally to the foldable bellows-shaped wrap a closed annular inner cavity is formed, which communicates with the internal space to the motor housing through a hole existing in the hermetic disk.

In operation, when fully dry submersible motor pump is submerged, the bottom of the air wrap will move upwardly to a place near the hermetic disc under the influence of the internal pressure in the camera of air, causing the air quantity inside the annular inner cavity of the wrapping to be directed into the motor housing, performing a pressure compensation.

The invention proposed in PI8900494-9 consisted in a breakthrough for its time.

However, despite the totally dry submersible motor pump be capable of working under higher pressure conditions, it has its performance limited. In other words, its pressure compensation capacity has a limit proportional to the volume of its foldable bellows-shaped wrap. In addition, the totally dry submersible motor pump proposed by the PI8900494-9 presents an extremely complex assembly, with a considerable amount of components, which makes its cost of manufacturing and assembling high.

To overcome all these technical drawbacks reported before, the BR PI0103598-3 proposes an amphibious pump with wet type electric motor, equipped with pressure equalization mechanism. It describes a modular pumping system, formed by the association in series of said amphibious pumps. According to the description, the amphibious pump is constructed with a wet type electric motor, housed inside the pumping chamber. The motor housing is internally filled with an aqueous solution and has a pressure equalizing mechanism, responsible for equalizing the fluid pressure inside the motor housing with the pumped fluid pressure inside the chamber where the motor is located in order to allow the amphibious pump operation under high pressure conditions.

The pump thus described in the application BR PI 0103598-3 works with an aqueous solution inside the motor chamber, and has a pressure equalizing assembly at its end opposite to the rotor. This pressure, equalizing assembly comprises a rubber mask with micro holes, which allow the exchange of water between the outer chamber and the motor chamber, with the objective to equalize the pressures.

But these pumps are limited to working with low temperature fluids and only with low voltage motors, in Brazil up to 1000 volts. In applications where the fluid to be pumped has a higher temperature and/or associated only with the supply of medium voltage (above 1000 volts up to 5000 volts) to drive the pump, the fluid to be used in the camera of the motor consists of a coolant which bears, no icing, low temperatures, and no boiling, high temperatures, normally oil. Such a need is known in the state of technology, because In motors like this there is a greater heating of the internal liquid of the motor chamber, leading to boiling aqueous liquid and the collapse of the motor.

Now, requiring the use of oil or coolant, the technical problem is evident, since it is not acceptable to release the oil. or this coolant in the environment, neither the motor may receive water or an aqueous liquid, when the operation of the pressure equalizing assembly, as described in BR P10103598-3. Thus, to date the amphibious pumps are limited to use low voltage motors.

On the other hand, the dry motors bring the problem of internal pressure, as hypothesized, for example, in the patent cited before, BR PI8900494-9, whose proposed solution requires the uprighting of the pump.

The fact is that when the internal temperature of the motor chamber increases, the coolant, whichever is, tends to expand. However, being a completely closed system, the motor chamber would break, with consequent collapse thereof.

Also, when such pumps are subjected to high pressures, there tends to be a difference in internal pressure of the housing where the motor and external pressure is, between the pump and motor housing. Elevated pressures tend causing the breakup of sealing seals or equivalent mechanisms.

Still, in the solution presented by the pump described in BR-PI0103598-3, the freezing or boiling of the internal fluid of the motor housing is an operating limiter.

SUMMARY

The present invention aims to overcome these obstacles by constructing an amphibious pump with wet type motor with coolant and provided with a mechanism for absorbing the expansion of said coolant inside the motor chamber. Briefly, the technical solution is to implement one expansion set in the motor chamber, dividing it into two chambers, provided with at least one expansion, joint between an internal chamber of the motor and an equalization inner chamber, this one provided with means, for equalizing the internal pressure to the pumped fluid. The electric motor is immersed in a coolant, usually oil, in a camera and the other camera is filled with the aqueous solution, and it communicates with the outside through, the equalizer assembly, which can, for example, comprise a mask rubber with micro holes, which allow the exchange of water between the outer chamber and the chamber of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may best be described with the help of figures, where:

FIG. 1 shows a cross section through the pump, where we see the pumping assembly (10), composed of the rotor (101), diffuser (102), regenerator taper (103), input housings (104) and outlet (105 ) and the flow tube (106) and the motor assembly (20), composed of a drive system through the electric motor (201) where the internal chambers of the motor are (A) and internal of equalization (B), pressure equalizing filter (202) and the expansion joint (203).

FIG. 2 is a detailed cutting showing only the motor assembly, where it is possible to better observe the internal chamber of the motor (A) and the internal equalization chamber (B).

FIG. 3 shows the position of the expansion joint (203) in the specific case of this typical construction, a diaphragm assembly (203) in its normal position (rest position).

FIG. 4 shows the position of the diaphragm assembly (203) in its expanded position.

FIG. 5 shows the position of the diaphragm assembly (203) in its compressed position.

FIGS. 3, 4 and 5 show the work of the diaphragm with respect to expansion of the oil when it varies its temperature.

DETAILED DESCRIPTION

The pump proposed in this invention consists of an inlet outer housing (104) and an output (105), provided with flanges at their ends, and connected through a flow tube not shown in the figures. This set of parts is called external set and are known to the state of technology, inside this outer set a drive (20) and pump (10) system is mounted, called motor assembly. Between the motor assembly and the outer set an annular space is formed through which flows the pumping flux. This construction is typical, of the state of technology.

The flanges are elements that link two components of a piping system, or piping to pump, allowing to be dismantled without destructive operations. The flanges are usually mounted in pairs and joined by screws, maintained the contact surface between two flanges under compression force in order to seal the connection. These elements normally used in the state of technology.

Internally, the pump consists of the pumping assembly (10) and the drive electric motor (201). The pumping assembly (10) is provided with a rotor (101), a diffuser (102) and a regenerator taper (103).

The rotor (101) has the function of giving motion to the fluid., transmitting the power generated by the electric motor (201) for the fluid through internal fins. The diffuser (102) has the function of decelerating the fluid and converting the kinetic energy into pressure. The regenerator taper (103) reduces the excess flow velocity, thus increasing the gain in pumping assembly pressure.

The motor drive system comprises an electric motor (201), a shaft (204), radial and axial plain hearings (205), closure covers of the electric motor (206), mechanical seal (207), diaphragm (203) and pressure equalization filter (202), This package has two internal chambers: In the internal chamber of the motor (A) is located the motor (201) which is completely filled with coolant known to the state of technology, usually an oil, which supports without freezing and low temperatures without getting into boiling and high temperatures. This chamber is hermetically sealed. At the internal equalization chamber (B) is located a pressure equalization filter, which allows pressure equalization (202) of the external chamber, through which the pumping flow passes, with the internal equalization chamber (B).

Between the inner chamber of the motor (A) and the equalization internal chamber (B) we have the diaphragm assembly (203), which expands or compresses as needed by the system depending on the temperature variation of the motor and expansion of the coolant.

Thus, during operation of the pump it is possible to be an exchange of the fluid pumped between the pumping outer chamber and the equalization internal chamber (B), according to the increase or decrease of the pumping pressure through the pressure equalizing filter (202). The increase or decrease of the pressure in the internal chamber of the motor (A) causes a displacement of the diaphragm (203) while balancing the pressure in the equalization internal chamber (B) with the exchange of fluid pumped between the outer pumping chamber and the equalization inner chamber (B).

With this construction it is possible to establish a pressure balance with no mixing of the coolant contained in the inner chamber of the motor (A) with the pumped liquid, enabling the operation at high pressures when associated with pumps in series, associated with high temperatures of the pumping fluid and/or also the need to provide medium voltage motors.

Well understood that the diaphragm (203) can be replaced by other technical means which perform the same function as any expansion joint.

Similarly, the pressure equalizing Alter (202), in typical mounting is in a rubber mask with micro holes, which allow the exchange of water between the outer chamber and the chamber of the motor. However, other equivalent means of pressure equalization can be used.

A constructive example is conducted with the use of a metallic expansion joint known in the state of technology. At an end of the internal chamber the expansion joint is closed and at the other end is opened, being mounted at one end of the inner chamber, isolating and forming the inner chambers of the motor (A), and the internal of equalization (B). Preferably, but without limitation, in order to prevent, that the motor shaft (204) from crossing the expansion joint (203), the construction of the equalization inner chamber is opposite to the rotor (101). 

1. An amphibious pump, equipped with pressure equalization, comprising: at least one expansion joint between an internal chamber of a motor and an internal equalization chamber; and means for equalizing internal pressure for pumped fluid.
 2. The amphibious pump according to claim 1, wherein the at least one expansion joint comprises a diaphragm.
 3. The amphibious pump according to claim 1, wherein the internal chamber of the motor comprises a hermetically sealed coolant.
 4. The amphibious pump according to claim 1, wherein the internal equalization chamber includes at least one pressure equalizing filter.
 5. The amphibious pump according to claim 4, wherein the at least one pressure equalizing filter comprises a rubber mask with micro holes, which allow exchange of water between an outer chamber and the internal equalization chamber. 